Secrets and Lies
by bookmaniac34
Summary: Demetra has somehow managed to grow up with Shadowhunters, without a single stele or seraph blade touching her skin. But when Clary came tumbling into their world, all of her secrets slowly started coming to the surface. Friendships will be tested, and torn apart. But nothing can split up a family. Right?


**A/N: So this is not my first fanfic but it is for Shadowhunters. Hope you enjoy it! Please read and review.**

 **P.S: This is a crossover with Percy Jackson and the Olympians and it might not use the same characters as the real story**

* * *

 _DEMETRA POV:_

I glanced up from my pot of flowers as Jace came into my room. I rolled my eyes. "Dude, ever heard of knocking?" He just laughed. I went back to my flowers when Alec and Izzy came in too. "Demetra, leave the plants, we got a mission," said Alec. I looked up and glared at the siblings. "Ok seriously, do you people know no manners?" Izzy and Jace shared a smirk while Alec gave me a stern look. I sighed. "Alright, when do we leave?" Jace gave me a look of triumph. "We leave in an hour," said Alec on his way out. I shook my head, laughing softly. Izzy went to go grab me something to wear. While Jace gazed at my flowers. "Weren't those the same ones you had like a month ago?" he asked curiously. "Shouldn't they be dead already?" I gulped. "I, uh got new ones, they're just the same kind," I said, trying to keep my voice even. He nodded slowly before leaving my room. Izzy came back in almost right after with two dresses. "Here, try this one," she said, handing me a tiny red dress. I took it from her and held up against my body. "Thanks Izzy but uh, where's the rest of it?" She laughed and elbowed me. "Oh come on Demi, it's stretchy," she replied. After about ten minutes of convincing, I reluctantly slipped into the dress while Izzy went to go get shoes. She came back with a pair of black high-heeled boots and two platinum blonde wigs. I grinned. "Nice Iz, demons dig blondes," I said, slipping the boots and the wig on. She smirked and put on her own wig. We quickly did our makeup and took off to go meet the boys. Alec caught up with us on the way and gave us a curious look. "What are you wearing on your head?" he asked, referring to the wigs. "What?" I said. "Demons dig blondes." Alec tugged at one of the strands of Izzy's wig. "Yeah but that's not blonde, it's white," he pointed out. We rolled our eyes. "No it's not white, it's platinum," I replied matter-of-factly. Alec held up his hands as if to say _whatever you say_. We met up with Jace in the entrance. "Nice call girls, demons dig blondes," he said. Alec crossed his arms. Jace quickly showed us what the demon currently looked like and where to find it. I walked over to the table that held my katanas and put them in their holsters while Alec grabbed his bow and arrow. Jace was in the corner, grabbing his seraph blade and Izzy tested out her whip a few times before we all headed out the door towards The Pandemonium.

* * *

Izzy and I stood on a ledge near the opening of Pandemonium, watching the crowds. I caught the demon in the corner of my eye and gestured to Izzy. She gave me a nod and we activated our glamour runes. We jumped from the ledge, landing softly on our feet. I quickly turned and sped off towards the club, where I could already see Alec in the entrance. I jogged up to him. "Hey where's Jace?" I asked, noticing he wasn't there. Alec pointed over to a van in the corner. Jace was standing in front of it, talking to a short little redhead. I went over to him. "How can I not know who you are?" I heard him say as I drew near. The girl scoffed. "Dude, has that line ever worked?" she asked, thinking he was hitting on her. Jace gave her a look of curiosity as I grabbed his arm. "Jace come on, let's go," I said, pulling him towards the club. He gave in and came back with me, leaving the redhead with a confused look on her face. We met up with Alec and Izzy and started towards the back of the club. We went through a curtain and found a whole herd of demons, including our target. Alec gave me and Izzy a look and we nodded. Together, we went up on the stage and pulled off our wigs. Izzy's raven hair fell over her shoulders while my white hair fell all the way past my waist. We began dancing and from the looks of it, doing a pretty good job distracting the guards. They came over to watch us as we kept dancing. "Watch out!" I heard a familiar voice shout. I quickly turned to see the redhead from earlier push our target away from Jace as he held up his blade to kill it. I sighed and jumped from the stage. The guards readied themselves as I grabbed my katanas from their holsters. I quickly fought off and killed a bunch while the strange girl grabbed a seraph blade from the floor. I watched as it activated for her. I shot her a confused glance and kept fighting. I saw her kill a demon and run out of the club. Jace finished off the last one. He gazed out the curtain where the redhead ran. I put my hand on his shoulder. "Go after her," I said. He nodded and took off while the rest of us packed up and left.

* * *

I had just finished cleaning the _ichor_ off of my katanas as Jace came into the room carrying the short redhead from Pandemonium. I gave him a look of curiosity as he made his way to the med bay to put her down. I set my blades down and quickly followed him into the room. I walked in to see him using his stele to rune her. I put a hand on his shoulder, making glance back at me. "What happened?" I asked. "Demon venom, she was stung back at her loft," he replied, turning to finish off the rune. He moved to remove her clothes nervously. I grabbed his hand. "I'll do it, just go grab me one of your t-shirts," I said. He nodded and went to go grab one. He came back two minutes later with a grey t-shirt in his hand. I took it from him and put it over the girl's head. Then I took off her other clothes and pulled the rest of it on. I heard Isabelle in the entrance and motioned for her to come in. She walked in, her heels clicking on the floor and laid a pile of clothes on the bedside for the girl. Jace stood up and left the room. "I'm going to find out who she is," he called over his shoulder. Me and Izzy exchanged looks. I grinned, Jace was interested in her. Izzy smiled back. I shot a glance at the girl, noticing that she was starting to wake up. I sat on the other side of the bed as she rubbed her eyes. She stared at us with wide green eyes. "Where am I?" she asked. "Your in a recovery room in The Institute," Izzy replied. The girl shot glances at the two of us. "Who are you two?" she asked. I laughed. "I'm Demetra, but you can just call me Demi," i said. The girl glanced over at Izzy. "And I'm Isabelle, I've never seen Jace so interested in a mundane," she said in response to the girl's curious look. I nodded in agreement. The girl opened her mouth. "I'm-" "Clary Fray," Jace said as he came into the room. "We know who you are." Alec was also in the corner of the room. "Why is there a mundane in the Institute?" he asked bitterly. Jace glared at Alec. "She's clearly not a mundane, the seraph blade lit up when she touched it," he said. "She still shouldn't be in here though," Alec said. Jace turned to face him. "Do me a favour, dial it down a notch," he said. Izzy stood up. "My brother doesn't have a dial, Alec I love you but it's true," she said. Alec wrapped his arm around Izzy. "Yeah I love you too but still," he said. "Okay here's something you'd never hear me say, please," said Jace. Alec glared at him and Clary. "What is with him, no seriously what is up with him?," he replied. Izzy looped her arm through his. "Walk with me big brother," she said, leading him out of the room. I stood up and laid a hand on Jace's shoulder. "I'm gonna take off too, lots of weapons to clean," I said, leaving the two alone. I left and went back to cleaning the blades. A few minutes later, I heard Clary's voice as she approached. "Okay Simon I'm coming," she said into her phone, trying to get out of the Institute. I heard Jace protesting from behind her. I shook my head, chuckling to myself. Who was this girl, and what exactly did she want?


End file.
